Windshield wiper motor



Feb. 9, 1943. s. SCHNELLV. 2,310,750

WINDSHIELD WIPER MOTOR Filed March 24, 1941 24 23 25 FIG 2 7 w 3 v I 38 2 2 22 46 79 so 4 5s A INVENTOR 55 STEVE SCHNE LL ATTORNEY atente Febo 9 i3 Steve $01,

erland, Mm, asslgnor to 1.

sec Corporation, St. Louis, Mo.. to comration of Delaware tion March 24, 1941, Serial No. 884,831

11 Claims. (01421-164) My invention relates to fluid pressure operated means and more particularly to one designed for actuating a windshield wiper blade or similar member.

One of the obiects 01 my invention duce an improved reciprocating motor operated by diflerential pressure and embodyin pistons or like elements having different areas.

is to pro Another object of my invention is to provide improved control means for a. valve employed in alternately placing a chamber in communication with the atmosphere and with a source of fluid having a diilerent pressure.

Still another object of my invention is to produce an improved reciprocating fluid pressure operated motor which so employs diflerent size pistons and cylinders that valve means is necessary only to control the flow of fluid under pressure to the larger cylinder and exhaust it therefrom in order to obtain the desired reciprocable movement.

A further and more specific object of my invention is to produce an improved reciprocating fluid pressure operated motor in which there is so embodied diiferent size pistons and cylinders and a control valve means that the motor can be operated by having fluid under pressure from the source in constant communication with the smaller cylinder.

Yet another object of my invention is to produce an improved reciprocating fluid pressure operated motor which is so constructed that simple and eilicient parking" means can be associated therewith to cause the motor to assume an inoperative position at one end only of its reciprocable movement.

Other objects of my invention will become apparent from the following description when taken in connection with the accompanying drawing in which Figure 1 is a side view of a motor embodying my invention, parts being removed to show certain internal construction; Figure 2 is a sectional view taken on the line 2--2 of Figure 1; and Figure 3 is a view showing a modified construction.

Referring to Figures 1 and 2, the casing i of the motor is provided with a large cylinder 2 and a small cylinder 3 having their axes in alignment. Within the large cylinder is a piston 4 carrying a. packing cup 5 and within the small cylinder is a piston 6 carrying a packing cup 'I. The pistons are connected together by a piston rod I which has formed on its intermediate portion gear teeth 9. The open end of the large cylinder i closed by a cap it.

The casing I is also provided with an integral cup-shaped portion ii having a boss i2 in which l3. Secured to the inner end of the shaft is a segment gear H, the teeth of which mesh with the teeth 8 on the piston rod. The outer end of shaft i2 is constructed to have attached thereto the usual windshield wiper blade or other member to be operated (not shown). The boss is provided with threads 15 in order that the casing may be attached to a support adjacent gear is provided with circumferentially spaced ribs i8 and i! positioned adjacent the periphery thereof and with an upstanding projection i8 adjacent the center thereof. the purpose of which will later become apparent.

The casing also has an integral portion is ad- Jacent the large cylinder 2 in which is formed chambers 20 and 2i. The portion l9 and the cup-shaped member II have associated therewith an overlying cover plate 22 and upon this cover adjacent the portion I! is mounted a separate casing member 23 provided with a valve chamber it This valve chamber has positioned therein a valve element 25 having a recess 25 in its under side and is held against cover plate 22 by a light leaf spring 21. This valve element is operated by an actuating rod 28 which is mounted for reciprocable movement in the upper part of the cup-shaped portion ii. The rod overlies the segment gear l4 and has a turned up end passing through an opening 29 in the cover plate 22 and connected to the valve element.

The chamber 24 in which the valve element 25 is positioned is in constant communication with the closed end of the small cylinder 3 by means of a tube 30. The valve chamber also is in constant communication with the source of air under pressure by a passage Ii and a conduit 32, which source may be a storage tank for a compressor. The passage 3| has associated therewith a metering valve 33 whereby passage 3i td the valve is iournaled a shaft chamber may be restricted. The metering valve of the large cylinder 2 by a passage 40. Within the windshield. The segment.

the chamber 36 is a valve element 4| for controlling communication between the passages 31, 38 and 39, all of which have open ends on the face of casing portion IS. The valve element has a recess 42 on its under side and is pressed against the surface of the casing portion |9 by a, fairly strong leaf spring 43. A portion 44 of the valve element extends to the exterior of the casing member 35 in order to provide means for actuation thereof. The recessed portion 42 of the valve element is such that when the valve element is in the position shown in Figure 2, it will place passages 31 and 39 in communication with each other. If the valve element should be moved to th left, passage 39 will be connected to the atmosphere passage 38 and passage 31 will be closed.

The valve actuating rod 28 previously referred to is provided with three spaced apart projections 45, 46 and 41 which extend toward the segment gear. The end projections 45 and 41 are adapted to cooperate with the flanges l6 and ii in order to prevent the actuating rod 28 from being moved except at the desired time. The central projection 46 is adapted to cooperate with a hairpin spring 38 pivoted on a pin 59 in the wall of the cup-shaped housing portion H. The legs 50 and of the spring extend on opposite sides of the central projection 36 on the rod and also projection i8 carried by the segment gear. The chamber 20 in the casing portion I9 is connected by a passage 52 to the interior of the cup-shaped portion ii and this latter casing portion is connected to the atmosphere by means of a tube 53.

When the valve element 25 is in the position shown, passage 31 will be uncovered and this passage will be in direct communication with the source of pressure through the valve chamber 24 If the valve is moved to the left, as viewed in Figure 2, so that the recess 26 in the underside of the valve element 2-5 is placed in communication with passage 31, this passage will then be in communication with the atmosphere by way of chamber 20, passage 52, the interior of the cupshaped casing portion H, and tube 53.

Referring now to the operation of the device, it is to be noted that the air pressure from the source is always in constant communication with the small cylinder by way of passage, 3|, valve chamber 2t and tube 30. This air pressure is preferably controlled by a pressure limiting valve interposed between the conduit 32 and the pressure source. If the parts of the fluid motor just described are in the positions shown in Figures 1 and 2, the large cylinder 2 will be in communication with the source as well as the small cylinder 3. The valve element 25 will be held by the hairpin spring 48 in the position shown due to the fact that the sector gear is in such a position that the projection ill will flex leg 5| and cause leg 56 to apply pressure to the projection 46 of the valve actuating rod.

With both cylinders in communication with the source of pressure, a resultant force will be effective on piston 4 tending to move both pistons to the right. This is due to the difference in area between the pistons. The area of the large piston 4 for best operation of the fluid motor should be approximately twice that 01 the small piston 5. As the pistons move to the right, shaft 3 will be rotated to swing the windshield wiper blade. During movement of the pistons to the right, the air in cylinder 3 will be pushed out and around into the large cylinder, the volume of which increases"twice as fast as the volume of the small cylinder decreases. Additional volume of air under pressure from the source will also enter the large cylinder and thus cause the piston therein to continue to move to the right.

As the pistons move, the sector gear will be rotated in a clockwise direction and this will bring the flange Hi to the position where it will lie to the left of projection 45 on the valve actuating rod. At the same time, the projection i8 on the sector gear moves away from leg 5| of the spring permitting said leg to engage projection 45 on the valve actuating rod. Continued movement of the pistons will move flange i! on the gear sector into a position at the. left of projection 41, thus preventing the actuating rod from moving to the left. At the same time flange l5 moves away from projection 45, projection i8 on the sector gear will engage leg of the spring and move it away from projection 46, thereby causing leg 5| to apply a force to the valve actuating rod tending to move it to the left. This valve actuating rod, however, will be unable to move due to flange When the pistons approach the right hand end of their stroke, flange I? will pass beyond projection 41. This will free the valve actuating rod so that it can be moved to, the left as viewed in the figures. This movement of the rod will take place quickly under the spring action of the hairpin spring.

Movement of the valve actuating rod will place the valve in a position where passage 31 is in communication with the atmosphere and the large cylinder will be exhausted. As soon as the pressure drops in the large cylinder, the air pressure in cylinder 3 acting on the small piston 6 will cause the pistons to move to the left. This movement of the piston causes the sector gear and shaft l3 to be moved in a counter-clockwise direction, thereby moving the windshield wiper blade back over the same surface it had previously wiped.

As the sector moves in a counter-clockwise direction. flange IE will become positioned to the right of projection 45, thus preventing the actuating rod from moving to the right. Rotation of the sector gear also results in the projection l8 moving away from the spring leg 50 and against leg 5| to place the spring under tension. At the time that the large piston 4 approaches the end of its stroke to the left, flange i6 will move beyond projection 45, thereby freeing the valve actuating rod and permitting the spring to quickly move the valve element 25 to the right where it will again be in the position shown in Figure 2. The valve element thus again places the large cylinder in communication with the source of pressure and as a result thereof, the pistons will be moved back to the right, repeating the cycle of operation. It is thus seen that the pistons will reciprocate back and forth repeatedly and so oscillate shaft l3 and the windshield, wiper blade that said blade will perform its work. The rate of movement of the piston rod in each direction is substantially the same due to the fact that the large piston has an area of substantially twice that of the small piston, thereby resulting in the forces tending to move the pistons in either direction being substantially the same.

It is to be noted in connection with the operation of the motor that the pressure in the large cylinder need only be great enough to move the windshield wiper and to push the air in the small cylinder around into the large cylinder. Thus, if five pounds of air pressure is sufficient to accomplish this, that is all that it would take to move the pistons to the right. The rapidity of reciprocation of the pistons depends upon the amount of air which is allowed to pass the metering valve 33 and also the amount of work that has to be done by the windshield wiper blade.

All the passages such as 31, 38, 39 and 40 are of such size that air can flow therethrough at as great a rate as the metering valve when fully open. Although the pistons are of different size, the amount of air used to operate the motor is the same as though the pistons were the same size as the small piston and each cylinder was exhausted to atmosphere on each stroke as is the present practice.

In connection with the particular control means for the valve element 25, it is to be noted that the valve is never allowed to be shifted until the desired time and then this shifting takes place very quickly under the action of the hairpin spring. In other words, the control is such that the valve element is always looked in its desired position until the time arrives that it must be shifted, at which time the shift is permitted to take place very rapidly in order to reverse the direction of movement of the pistons.

When it is desired to stop the motor and park the windshield wiper blade, all that is necessary is to shift the valve element 6| from its position shown in Figure 2 to a. position to the left thereof so that passage 39 will be connected to passage 38. The large cylinder will thus be vented to atmosphere and regardless of the position of the valve element 25 or the position of the pistons, both pistons will be moved to the left and assume the positions shown in Figure 1. This 'is brought about due to the fact that the small cylinder is at all times in communication with the source of pressure. The spring for the valve element M is strong enough to maintain the valve element seated and prevent any leakage thereby when the passage Ell is covered. Since the size of passage 31 is quite small, the force necessary to prevent leakage can also be small. It is thus seen from the structure that the parking of the windshield wiper blade is obtained by a very simple arrangement and it is not necessary for the pistons to complete any cycle of operation to reach their parked positions. As

- soon as the valve element M is shifted to exhaust the large cylinder, the pistons will immediately move directly to the positions shown in Figure 1.

It has been found desirable to operate the fluid motor by compressed air which is laden with a small amount of oil. Thus the parts will be well lubricated since the exhausted air during the operation of the motor is passed through the casing portion enclosing the gear sector and other working parts before it is passed to atmosphere through tube 53.

In the modification shown in Figure 3, which is a somewhat diagrammatic view, the control valve element and parking valve element are of slightly diiierent construction. The casing 54 is provided with a large cylinder '55 and a small cylinder 56 in which are the pistons 51 and 58 connected together by the rod 59. The portion 60 of casing 56 has mounted thereon the valve casing member 6! which is connected to the fluid pressure source by a passage 62 controlled by the metering valve element 63. A plate 64 is interposed between the casing portion 60 and the valve casing member 6| and mounted in this in the chamber 65 is a valve element 66 having recesses 61 and 6B in its under side, said valve being biased onto the plate by a light spring 69. A through passage 10 is also provided in the valve element.

The small cylinder 58 is connected to the valve chamber 65 by a passage H and the large cylinder is connected to said valve chamber by two passages 12 and I3. All of these passages are controlled by the valve element 66. The casing portion 60 has a chamber 14 which constantly.

communicates with the atmosphere by a passage 15 and with the recess 68 in the valve element by a hole 16 in plate 64. The passage ll leading to the small cylinder has a small branch passage I1 which is not controlled by the valve element and constantly places passage H in communication with the valve chamber 65. The valve element 56 is connected to rod 18 which is actuated by the same structure disclosed in Figures 1 and 2, said structure not being shown in this modification.

The parking valve comprises a slide valve element 19 carried by the casing and extending across the passages H, 12, and 13. This valve element has two elongated slots and 8! and an intermediate hole 82. When the slide valve element is in the position shown, the passages H,

l2, and 13 are all open. When the valve element is moved inwardly to the right, passage 12 will be cut oil and the large cylinder will be placed in communication with atmosphere only by way of chamber 14. Passage II will remain open.

, In the operation of the modified construction with the parts in the positions shown, air under pressure from the source is in communication with both cylinders. to be moved to the right. When they approach the right hand end of, the stroke, the valve element 56 will be shifted to the left by the actuating rod 18 and the structure shown in Figures 1 and 2. This will cause the'passage 13 leading to the large cylinder to be cut ofl from the source of pressure and placed in communication with the atmosphere by way of the recess 68 in the valve element. element also causes the recess 61 of the valve element to move to a position where communication between passages and 12 is cut off and passage ll placed in direct communication with valve chamber 65 and the pressure source by way of recess 61. Thus with fluid under pressure effective on the small cylinder only, the pistons will be moved to the left and when they approach the end of their stroke valve element 66 will be shifted back to the position shown in Figure 3, thus again connecting the large cylinder to the source of pressure and causing the cycle to be repeated.

It is to be noted in the modification that the valve element 66 controls the flow of air to both cylinders although regardless of the position of the valve element the small cylinder is always in communication with the source of pressure. When the large'cylinder is connected to the source of pressure, the small cylinder will also be connected to the source through the large cylinder. When the large cylinder is cut off from the source, the small cylinder will be placed in direct communication with the source. Thus the operation of the motor of Figure 3 is the same as that of the motor shown in Figures 1 and 2 with the exception, however, that'the air which is pushed out of the small cylinder has a separate passage to enter the large cylinder and does not need to be pushed through the valve chamber 65.

This will cause the pistons The new position of the valve.

When the slide valve element 19 is pushed in to park the motor, the large cylinder will be immediately vented to atmosphere regardless of the position of the valve element 66. If the valve element 66 should be in the position shown in Figure 3, air under pressure in the small cylinder will be built up through the small passage 11 which is only about five thousandths of an inch in cross-sectional area. If the valve element 66 should be in its left end position, the small cylinder will be in communication with the source through the recess 61 in said valve element. Thus it is seen that the purpose of the small passage H is to insure that the pistons will be moved to the left end of the stroke and held in such position in the event that the valve element 66 should be in the position shown in Figure 3 at the time the slide valve element 19 is pushed in to park the windshield wiper blade. When parking takes place with the valve element 65 in the position shown, the parking action will be slower than if the valve element 66 were in its left hand position since the fluid under pressure from the source will enter the small cylinder at a slower rate.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a fluid motor, two chambers of different cross-sectional area, movable elements in said chambers and connected together for simultaneous movement, a source of pressure different from atmosphere, means for causing fluid pressure from the source to be constantly effective in the smaller of said chambers, means including valve means controlled by the movement of the mov able elements when being moved by diflerential pressure for alternately placing the larger of said chambers in communication with the source and with the atmosphere, and other valve means operable independently of the first valve means and notwithstanding the condition thereof to cause diflerential pressure to position the movable elements at one end of their stroke.

2. In a fluid motor, two chambers of difierent cross-sectional area, movable elements in said chambers connected together for simultaneous movement, a source of pressure different from atmosphere, means for causing fluid pressure from the source to be constantly effective in the smaller of said chambers, means including valve means controlled by the movement of the movable elements when being moved by diiferential pressure for alternately placing the larger of said chambers in communication with the source and with the atmosphere, and other valve means for placing the larger of said chambers in communication only with the atmosphere notwithstanding the condition of the first named valve means.

3. In a fluid motor, two chambers of different cross-sectional area, movable elements in said chambers connected together for simultaneous movement, a source of fluid pressure different from atmosphere, means for causing fluid pressure from the source to be constantly effective in the smaller of said chambers, means including valve means for alternately placing the larger of said chambers in communication with the source and with the-atmosphere, means controlled by the reciprocable movement of the movable elements for causing the valve means to place the larger chammr in communication with the source when the element in the smaller chamber has been moved by the action of a dif= ferential pressure thereon to the end of its stroke and for placing the larger chamber in communication with the atmosphere when the element in the larger chamber has been moved by the action of a differential pressure to the end of its stroke, and manually-controlled valve means for placing the larger chamber in communication with the atmosphere notwithstanding the condition of the first named valve means.

4. In a fluid motor, two cylinders of difiercnt diameter, pistons in said cylinder connected together for simultaneous movement, a source of fluid pressure, conduit means for placing the smaller cylinder in constant communication with the source, conduit means for connecting the large cylinder to the source, valve means controlled by the movement of the pistons and associated with the last named conduit means for alternately placing the large cylinder in communication with the source and with atmosphere, and other valve means for closing the second conduit means and placing th large cylinder in communication with atmosphere independently of the first valve means.

5. In a fluid motor, two cylinders of difl'erent diameter, pistons in said cylinder connected together for simultaneous movement, a source of fluid pressure, conduit means for placing the smaller cylinder in constant communication with the source, conduit means for connecting the large cylinder to the source, valve means controlled by the movement of the pistons and associated with the last named conduit means for alternately placing the large cylinder in communication with the source and with atmosphere,

and manuaily-controlled valve means for causing the fluid pressure to so act on the pistons as to move them to one end of their stroke and maintain them in such position notwithstanding the condition of the first named valve means.

6. In a fluid motor, two chambers of diilerent cross-sectional area, movable elements in said chambers connected together for simultaneous movement, a source of fluid pressure different from atmosphere, means for causing fluid pressure from the source to be constantly effective in the smaller of said chambers, valve means for alternately placing the larger of said chambers in communication with the source and with the atmosphere, means for controlling said valve means by the reciprocable movement of the elements and comprising an actuating member, a spring, means operable by movement or the elements in one direction to cause said spring to apply a force to move the slidable member in one direction and means operable by movement of the elements in the opposite direction to cause said spring to apply a force to move the slidable member in the opposite direction. and locking means for preventing the movement of the slidable member by the spring until the elements approach'the end of their stroke.

7. In a reciprocating fluid motor including reciprocable elements, a source of fluid pressure difierent from atmosphere, reciprocable valve means for controlling the application of pressure to operate the reciprocable elements, a slidable valve actuating member, positioned to have its lin of slide parallel with the axis of the reciprocable elements, pivotally mounted spring means having two free ends engageable with the actuating member, means operable by the movement of the elements in one direction for causing one free end of said spring means to apply a force to move the actuating member in one direction and means operable by the movement of the elements in the opposite direction for causing the other free end of said spring means to apply a force to move the actuating member in the oppositedirection, and locking means for preventing movement of the actuating member by the spring means until the elements approach the end of their stroke.

8. In a reciprocating fluid motor including reciprocable elements, a source of fluid pressure different from atmosphere, r'eciprocable valve means for controlling the application of fluid pressure to operate the reciprocable elements, a valve actuating member, a pivoted hairpin spring having its ends cooperable with the actuating member, means operable by the movement of the elements in one direction for causing one end of the spring to apply a force to move the actuating member in one direction, means operable by movement of the elements in the opposit direction for causing the other end of the spring to apply a force to move the actuating member in the opposite direction, and locking means for preventing movement of the actuating member by the spring until the elements approach the end of their stroke.

9. In a reciprocating: fluid motor including re- .ciprocable elements, a sourceof fluidmressure difl'erent from atmosphere, reciprocable .valve means for controllin the application of fluid pressure to operate the reciprocable elements, a valve actuating member, a pivoted hairpin spring having its ends cooperable with the actuating member, means operable by the movement of the elements in one direction for causing one end of the spring to apply a force to move the actuating member in one direction, a member oscillatable by the reciprocation of the elements, means on the oscillatable member for causing one leg of the spring to apply a force to move the actuating member in one direction when the oscillatable member moves in one direction and for causing the other leg of the spring to apply a force to move the actuating member in the opposite direction when the oscillatable member moves in the opposite direction, and cooperating means on the oscillatable member and the actuating member for preventing movement of said actuating member by the spring until the elements approach the end of their stroke.

10. In a fluid motor, two cylinders of different diameters, pistons in said cylinders connected together for simultaneous movement, a source of fluid pressure, first conduit means for placing the end of the large cylinder in communication with the source, second conduit means for placing the end of the small cylinder in communication with the source at all times, third conduit means for placing the cylinders in communication with each other and including a portion of the second conduit means, valve means for controlling said conduits, and means for moving the valve means by the movement of the pistons, said valve means being provided with means for so controlling all the conduit means that when the pistons approach one end of their stroke the large cylinder will be in communication with the source by the first conduit means and with the small cylinder by the third conduit means and when the pistons approach the'other end of their stroke the large cylinder will be vented to atmosphere and the small cylinder will be in communication only with the source and by way of the second conduit means.

11. In a fluid motor, two cylinders of difierent diameters, pistons in said cylinders connected together for simultaneous movement, a source of fluid pressure, first conduit means for placing the end of the large cylinder in communication with the source, second conduit means for placing the end of the small cylinder in communication with the source at all times, third conduit means for placing the cylinders in communication with each other and including a portion of the second conduit means, valve means for controlling said conduits, means for moving the valve means by the movement of the pistons, said valve means being provided with means for so controlling all the conduit means that when the pistons approach one end of their stroke the large cylinder w'lll be in communication with the source by the first conduit means and with the small cylinder by the third conduit means and when the pistons approach the other end of their stroke the large cylinder will be vented to atmosphere and the small cylinder will be in communication only with the source and by way of the second conduit means, and means including other valve means operable independently of the first valve means for simultaneously venting the large cylinder to atmosphere and preventing communication between th cylinders.

STEVE SCHNEIL. 

